The objective of this program is to continue the multidiscipline approach to the study of disease in man which has been underway since 1964. The disciplines include biochemistry, immunology, genetics, hematology and metabolism. Diseases due to single gene defects and aneuploidy have been selected for study since these are likely to provide discrete deviations from the norm. Altered gene products or genetic mechanisms will be sought because such diseases represent experimental models. They are likely to provide insights into the pathophysiology of the disease under study into genetic determinants of normal growth and development, and into structure-function relations at the molecular level.